1. Field of the Invention
The invention relates generally to the clamping of elastomeric hose and tubing to fixtures and hose coupling devices and to the use of bands of heat shrinkable polymer to provide a constrictive force about elastomeric hose and tubing. More particularly, this invention relates to an improved heat shrinkable hose clamp where a device is incorporated to get positive indication of when the heat shrinkable clamp is adequately heated to effect its intended purpose. Specifically, the invention relates to a heating indicator, that forms part of the heat shrinkable hose clamp, that indicates proper installation including adequate heat application to the clamp to effect adequate clamping force.
2. Description of the Prior Art
Elastomeric hose and tubing, hereinafter generically referred to as hose, are commonly used to convey various fluids, where those fluids are under a variety of pressures and temperatures, as part of a fluid transport system. For these systems to be operable, the connections between hoses and the items with which the hoses fluidly communicate must be fluid tight and able to resist separation that would otherwise occur because of the influence from the fluid pressure, or blow-off, as well as surrounding environment, or pull-off. Commonly, these connections are made by placing the open end of the hose over a stem or coupling insert. The hose and the associated stem or insert are ordinarily sized and shaped to allow the opening of the hose to slip over the stem or insert and to seat with a snug fit. For systems operating at certain pressures and in certain environments, nothing more is required. More typically, however, a hose clamp is installed near the open end of the hose, urging the hose more tightly upon the stem or insert to resist leakage, blow-off, and pull-off.
Hose clamps have been produced in various sizes, shapes, and materials. One style of hose clamp is formed of a band of heat shrinkable polymer. Hose clamps of this type are more fully discussed in U.S. Pat. No. 5,340,167, Morse, which is incorporated herein by reference. Such a material is mechanically expanded, stretched or oriented and formed into a band. Once the temperature of the material forming the band is sufficiently elevated, a portion of the energy, that is put into the material through the orientation process, will be released, as manifest by the band tending to shrink to its original or pre-oriented dimensions. The temperature at which this shrinkage begins is commonly referred to as the release temperature, as that is the temperature at which the stored energy of orientation is released. In the case of the material formed into a ring or band, this temperature can logically be referred to as the diameter reducing release temperature.
In use; the heat shrinkable hose clamp is placed about an end of a hose; the hose is placed upon some type of hose insert or stem, such as would be encountered on an automotive radiator, hose-to-hose connector, or other device or mechanism to which a fluidic connection is desired; and heat is applied to the clamp until shrinkage occurs and appears or is guessed to be sufficient.
On any hose clamp installation, the one doing the installation ordinarily relies on past performance of similar or like clamps to be satisfied that the installation, just effected, will produce the desired result (i.e., maintain the hose connection against the expected environment and maintain a fluid-tight seal). There is rarely, if any, feedback to the installer that the particular installation at hand will prove to be satisfactory. Feedback, of this type, would have the obvious advantage of improving quality in hose connections. This is particularly true where heat shrinkable hose clamps are involved, as heat shrinkable hose clamps are not only susceptible to the problems that would interfere with any hose clamp installation being satisfactory (e.g., mis-sizing of a clamp, misalignment of the clamp, or the clamp itself being faulty), it also has the consideration of proper application of heat. If the heat applied is insufficient or poorly distributed about the heat shrinkable clamp, then conceivably, the clamp will not produce adequate clamping force to produce the desired result.
Co-pending application, Ser. No. 08/057,242, discusses the incorporation of a shrinkage indicator comprising a viscous material interposed between the hose and the clamp. The viscous material softens when heated, but remains adequately thick so that substantial flow only occurs either out from under the clamp, becoming visible along the edges, or through breaches in the clamp, becoming visible on the outer surface of the clamp adjacent to the breaches, upon adequate changing force being produced. While, such an indicator imparts many advantages to the clamp, it is subject to additional expense in manufacture and some difficulty with quality control and aesthetics.
Accordingly, there remains the need to produce positive indication that the heat shrinkable hose clamp, just installed, has been appropriately heated, and therefore is likely to produce adequate clamping force to achieve the desired result, while at the same time being cost efficient, aesthetically pleasing and easily susceptible to the maintenance of high quality.